387 research outputs found
Kharkiv region of Ukraine in the aspect of a polycentric development model
This article is devoted to the analysis of a model of regional
development of Kharkiv region of Ukraine, which is monocentric, and the rationale for
the formation of polycentrism in the region. The city of Kharkiv and urban areas as
centers of growth in the region are considered in the articl
Transport properties of the azimuthal magnetorotational instability
The magnetorotational instability (MRI) is thought to be a powerful source of turbulence in Keplerian
accretion disks. Motivated by recent laboratory experiments, we study the MRI driven by an azimuthal
magnetic field in an electrically conducting fluid sheared between two concentric rotating cylinders.
By adjusting the rotation rates of the cylinders, we approximate angular velocity profiles ω ∝ r
q
. We
perform direct numerical simulations of a steep profile close to the Rayleigh line q & −2 and a quasiKeplerian
profile q ≈ −3/2 and cover wide ranges of Reynolds (Re ≤ 4 · 104
) and magnetic Prandtl
numbers (0 ≤ Pm ≤ 1). In the quasi-Keplerian case, the onset of instability depends on the magnetic
Reynolds number, with Rmc ≈ 50, and angular momentum transport scales as √
PmRe2
in the turbulent
regime. The ratio of Maxwell to Reynolds stresses is set by Rm. At the onset of instability both
stresses have similar magnitude, whereas the Reynolds stress vanishes or becomes even negative as
Rm increases. For the profile close to the Rayleigh line, the instability shares these properties as long
as Pm & 0.1, but exhibits a markedly different character if Pm → 0, where the onset of instability is
governed by the Reynolds number, with Rec ≈ 1250, transport is via Reynolds stresses and scales as
Re2
. At intermediate Pm = 0.01 we observe a continuous transition from one regime to the other, with
a crossover at Rm = O(100). Our results give a comprehensive picture of angular momentum transport
of the MRI with an imposed azimuthal field
GEOGRAPHICAL ANALYSIS OF FOREST FLORA OF THE CENTRAL CISCAUCASIA
Abstract. Aim. Forest flora of the Central Ciscaucasia in General is a relict, geographically situated in the steppe zone. Composing flora elements have different types of habitats, concentrated in the natural physical-geographical unit where isolated from the main habitats. Comparative analysis of the geographic, ecological and systematic components of forest flora will provide data about the correlation of these parameters identify the leading group. Location. The Central CiscaucasiaMethods. We made the geographical and systematic ranges of forest flora of the Central Ciscaucasia and their comparative analysis is conducted.Results. Geographical analysis of forest flora of the Central Ciscaucasia revealed 16 geographical elements, grouped in 6 categories, among which is the predominant group of boreal geographical elements. It is established that the leading geographical elements are Euro-Caucasian, Caucasian and Sub-Caucasian, numbering 189 species, and are half of the flora. Comparison with ecological spectrum showed that the sequence geographical elements completely different, here leading positions are occupied Northern species as ecologically more conservative, and the Caucasian demonstrate ecological plasticity. In a systematic relation matched warheads geographical and systematic spectra. The scope of the results. The results may be used in comparative Floristics, in its theoretical part in adjusting themodels of the Genesis of the flora.Conclusions. Thus, half of the geographical elements of the forest flora of the Central Ciscaucasia are linked in their distribution of Caucasian floristic province (Euro-Caucasian, Caucasian and Sub-Caucasian). These same geographical elements to predominate in the head part of the spectrum families. Most geographical elements have low ecological plasticity species, their components, do not go beyond the forest plant association, but geographical elements head part of the geographical range are the most ecologically plasticity
Study of psychological status of tsu students from exercise therapy group
The present article contains the results of ascertaining study, aimed at identification of the psychological characteristics of students engaged in groups of exercise therapy. It has been established that students with poor health differ greatly in psychometric characteristics from the group of students who do not have any problems with their health. These differences are most pronounced in the findings obtained by means of questionnaires of constructive thinking and level of subjective control. Students who train in the groups of exercise therapy, need special forms of organization of the educational process involving psychological methods
Oxygen-conducting Composites Based on Me2(WO4)3 (Me = Sm, Al)
Composites Sm2(WO4)3-WO3 and Al2(WO4)3-WO3 were prepared by the solid-state method and a systematic study of their electrotransport properties has been carried out. A sharp increase in the oxygen-ion conductivity is observed in composites Sm2(WO4)3–WO3 at small WO3 values (about 10 mol.%). This effect is probably caused by formation of the non-autonomous interface phase covering grain boundaries of Sm2(WO4)3. These composite O2− – electrolytes are perspective materials for high temperature fuel cells. Тhe composite effect is absent in the Al2(WO4)3–WO3 system. This is probably due to the negative thermal expansion coefficient of Al2(WO4)3, which prevents the formation of a continuous high-conducting microphase film.
Keywords: composites, ionic conductivity, heterogeneous doping, microphas
The formation and development of the managerial personnel reserve on the example of the Tatarstan republic
The article describes the practice of formation the personnel reserve in government and administration of the Tatarstan Republic. Also presents an analysis of candidates for inclusion on the roster consisting of three interconnected successive stages- preparatory, competitive and evolving. The authors emphasize the usage of working with a reserve by the structural subdivisions of the human control and power, as well as individual activity types of reservists
Broad Line Emission in Low-Metallicity Blue Compact Dwarf Galaxies: Evidence for Stellar Wind, Supernova and Possible AGN Activity
We present spectra of a large sample of low-metallicity blue compact dwarf
galaxies which exhibit broad components in their strong emission lines, mainly
in Hbeta, [O III]4959, 5007 and Halpha. Twenty-three spectra have been obtained
with the MMT, 14 of which show broad emission. The remaining 21 spectra with
broad emission have been selected from the Data Release 5 of the Sloan Digital
Sky Survey. The most plausible origin of broad line emission is the evolution
of massive stars and their interaction with the circumstellar and interstellar
medium. The broad emission with the lowest H luminosities (10^36 -
10^39 erg/s) is likely produced in circumstellar envelopes around hot Ofp/WN9
and/or LBV stars. The broad emission with the highest Halpha luminosities
(10^40 - 10^42 erg/s) probably arises from type IIp or type IIn supernovae
(SNe). It can also come from active galactic nuclei (AGN) containing
intermediate-mass black holes, although we find no strong evidence for hard
non-thermal radiation in our sample galaxies. The oxygen abundance in the host
galaxies with SN candidates is low and varies in the range 12 + log O/H = 7.36
- 8.31. However, type IIn SN / AGN candidates are found only in galaxies with
12 + log O/H < 7.99. Spectroscopic monitoring of these type IIn SN / AGN
candidates over a time scale of several years is necessary to distinguish
between the two possibilities.Comment: 50 pages, 6 figures. Accepted for publication in the Astrophysical
Journa
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